478 Mr. D. L. Chapman : A Contribution 



The solution of (C) is 



5*, AJL .loo- vV+ y/p^.ypo- s/p 



^Poo' = \/p x - V^oo V>0+ Vp w 



The last equation is not at present of much practical 

 importance. 



What we require to know in order that we may be able 

 to test the theory of electrocapillarity by a direct comparison 

 of the experimental values of surface tension with those cal- 

 culated from the theory, is the magnitude of the charge on 

 the double-layer condenser for a given difference of potential 

 between the solution and the metal. 



By integrating Poisson's equation between and co we 

 obtain 



ix ' ' K 



in which Q is the charge on unit surface of the solution. 

 But 



dv d nt 



== : loo-^ . 



dx dx e ° e 



Substituting in this equation the value of ~=- log e po. 

 obtainable from (C), we deduce that ®x 



A more convenient form of the above equation is 



eV ev 



Pc 



<*WS 



IT 



2Rt - 2 nt 



e -e ),.... (D> 



w T here V is the difference of potential between the solution 

 and the mercury. 



Calculation of the Surface Energy of Mercury in 

 contact with an Electrolyte. 



The surface energy of the mercury in a capillary electro- 

 mometer can be deduced in the following way. 



Suppose that a layer of mercury A is in contact with a 

 solution of potassium chloride which also contains mercurous 

 chloride at a very low concentration. Assume also that the 

 means exist for increasing and diminishing the surface of 

 the mercury in contact with the potassium chloride. In the 



